Equipment are necessary to adhere to a protocol so the interrupt-request (IRQ) traces can be shared. The PCI bus includes 4 interrupt lines, INTA# via INTD#, all of which can be obtained to every gadget. Up to 8 PCI equipment share the same IRQ line (INTINA# by INTINH#) in APIC-enabled https://nathanlabsadvisory.com/hitrust/